title: Degrading magnesium screws ZEK100: biomechanical testing, degradation analysis and soft-tissue biocompatibility in a rabbit model.
abstract: Magnesium alloys are promising implant materials for use in orthopaedic applications. In the present study, screws made of the Mg-alloy ZEK100 (n = 12) were implanted in rabbit tibiae for four and six weeks, respectively. For degradation analysis, in vivo µ-computed tomography (µCT), a determination of the weight changes and SEM/EDX examinations of the screws were performed. Screw retention forces were verified by uniaxial pull-out tests. Additionally, soft-tissue biocompatibility was estimated using routine histological methods (H&E staining) and the immunohistological characterization of B- and T-cells. After six weeks, a 7.5% weight reduction occurred and, in dependence of the implant surrounding, the volume loss (µCT) reached 9.6% (screw head) and 5.0% for the part of the thread in the marrow cavity. Pull-out forces significantly decreased to 44.4% in comparison with the origin value directly after implantation. Soft tissue reactions were characterized by macrophage and lymphocyte infiltration, whereas T-cells as well as B-cells could be observed. In comparison to MgCa0.8-screws, the degradation rate and inflammatory tissue response were increased and the screw holding power was decreased after six weeks. In conclusion, ZEK100-screws seem to be inferior to MgCa0.8-screws, although their initial strength was more appropriate.
authors.affiliation: Small Animal Clinic, University of Veterinary Medicine Hannover, Hannover, Germany. janin.reifenrath@tiho-hannover.de
authors.forename: Janin
authors.initials: J
authors.lastname: Reifenrath
authors.forename: Nina
authors.initials: N
authors.lastname: Angrisani
authors.forename: Nina
authors.initials: N
authors.lastname: Erdmann
authors.forename: Arne
authors.initials: A
authors.lastname: Lucas
authors.forename: Hazibullah
authors.initials: H
authors.lastname: Waizy
authors.forename: Jan M
authors.initials: JM
authors.lastname: Seitz
authors.forename: Alexander
authors.initials: A
authors.lastname: Bondarenko
authors.forename: Andrea
authors.initials: A
authors.lastname: Meyer-Lindenberg
mesh_terms: D000497:Alloys / Q000737:chemistry*; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002118:Calcium / Q000737:chemistry; D005260:Female; D007150:Immunohistochemistry; D007249:Inflammation; D008214:Lymphocytes / Q000166:cytology; D008264:Macrophages / Q000166:cytology; D008274:Magnesium / Q000737:chemistry; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011817:Rabbits; D013977:Tibia / Q000473:pathology; D013997:Time Factors; D055114:X-Ray Microtomography
chemical_list: D000497:Alloys; D001672:Biocompatible Materials; D008274:Magnesium; D002118:Calcium